Mercedes-Benz 300SL Roadster

David Undercoffler / Los Angeles Times

This 1957 Mercedes-Benz 300SL Roadster was formerly owned by Robert Stack, star of "The Untouchables," and later "Unsolved Mysteries." After his death it passed to the Petersen Museum, which is now selling it at auction. The car is estimated to sell for between $600,000 and $800,000.

This 1957 Mercedes-Benz 300SL Roadster was formerly owned by Robert Stack, star of "The Untouchables," and later "Unsolved Mysteries." After his death it passed to the Petersen Museum, which is now selling it at auction. The car is estimated to sell for between $600,000 and $800,000. (David Undercoffler / Los Angeles Times)

This 1957 Mercedes-Benz 300SL Roadster was formerly owned by Robert Stack, star of "The Untouchables," and later "Unsolved Mysteries." After his death it passed to the Petersen Museum, which is now selling it at auction. The car is estimated to sell for between $600,000 and $800,000.